need help in chem

1. What happens to the kinetic energy of a moving bus as it comes to a stop?

2. If energy is never destroyed, why are we encouraged to conserve energy?

3. An example of an endothermic process is:

A. digestion of food

B. burning of coal

C. melting of ice

D. all of the above

4. In an experiment, if the initial temperature is 72.1 EC and the final temperature is

26.9 EC, what is the temperature change (Δt) for this experiment?

5. In which of the following is energy (heat) released?

A. evaporation of water from your skin

B. conversion of carbon dioxide gas into dry ice (solid carbon dioxide)

C. digestion of food

D. all of the above

E. only B and C

6. If 25 g of iron (c = 0.45 J/g@EC) and 25 g of silver (c = 0.24 J/g@EC), both at room

temperature, are dropped into separate glasses of 50 mL of water at 90 EC, which

metal will reach the higher temperature?

Explain.

7. How does the amount of energy needed to heat a sample of water from 16 EC to

42 EC compare to that needed to heat this same sample from 51 EC to 77 EC?

Explain.

8. A 280-g metal bar requires 5.31 kJ to change its temperature from 21 EC to 100 EC. What is the specific heat of the metal?

9. Consider a sample of water in the gaseous state. Describe what happens to the

molecules in the sample as the sample is slowly cooled until it liquefies and then

solidifies.

10. What important idea is behind the practice of writing balanced chemical

equations?

11. Convert each of the following word equations into a chemical equation and then

balance it. Indicate the physical state of each reactant and product.

a) sodium metal + oxygen gas ÷ sodium oxide

b) sodium bicarbonate ÷ sodium carbonate + water + carbon dioxide

c) hydrochloric acid + nickel metal ÷ hydrogen gas + aqueous nickel chloride

12. Balance each of the following chemical equations. Classify each reaction as

combination, decomposition, combustion, single displacement or double

displacement.

a) Na3PO4(aq) + BaCl2(aq) ÷ NaCl(aq) + Ba3(PO4)2(s)

b) SO2(g) + O2(g) ÷ SO3(g)

c) H2CO3(aq) + KOH(aq) ÷ K2CO3(aq) + H2O(l)

d) Fe2O3(s) + Al(s) ÷ Fe(s) + Al2O3(s)

e) C3H5(NO3)3(l) ÷ CO2(g) + H2O(g) + N2(g) + O2(g)

13. In which of the following compounds are the electrostatic attractions between

oppositely-charged ions likely to be the strongest?

A. LiCl

B. Li2O

C. FeO

D. FeCl2

14. Which of the following substances is likely to be insoluble in water?

A. potassium bromide

B. sodium carbonate

C. lead(II) sulfide

D. copper(II) acetate

E. all of these

15. When FeS(s) reacts with HCl(aq) the products of this reaction are:

A. FeCl(aq) and HS(aq)

B. FeCl2(s) and HS(aq)

C. FeCl(aq) and H2S(aq)

D. FeCl2(aq) and H2S(aq)

16. Classify each of the following reactions as combination, decomposition,

combustion, single displacement or double displacement, then complete and

balance each equation. Indicate the physical state of each product.

a) Mg(OH)2(s) + H3PO4(aq) ÷

b) C2H6O2(l) + O2(g) ÷

c) Cl2(aq) + NaI(aq) ÷

d) Ag(s) + O2(g) ÷

17. When each of the following pairs of aqueous solutions is mixed, a precipitate

forms. Write the correct chemical formula for the precipitate in each case.

iron(III) perchlorate and potassium hydroxide ____________

nickel acetate and sodium sulfide ____________